Extraction Fan Assembly for an Animal Husbandry Barn

ABSTRACT

An animal barn includes air inlets which are filtered to extract pathogens and a plurality of extraction fans for generating an air stream so as to draw replacement air into the containment area through the air inlets. Each fan has a housing mounted in a wall with an outlet duct extending through the wall to an outlet opening outside the wall. A damper flap is mounted on the fan suspended by a hinge at an upper edge so as to extend in a closed position across the opening in a mounting plate. The damper flap is movable to an open position under forward air flow from the fan and closes against a resilient deformable seal to seal the damper flap to prevent reverse flow of pathogen contaminated air through the fan housing when the fan is shut off. An adjustable abutment member can act to hold the flap partly open against opposing wind forces during low fan operation.

This invention relates to a fan construction for use in an animal husbandry barn.

Typically such barns comprise a containment area; a plurality of air inlets into the containment area and a plurality of extraction fan constructions for generating an air stream exiting the containment area so as to draw replacement air into the containment area through the air inlets. In many cases each air inlet has an air filter system for extraction from incoming air of pathogens so as to reduce transmission of disease to the animals

BACKGROUND OF THE INVENTION

In recent years prevention of disease to animal husbandry barns has reached the extent where attempts are made to ensure that all air entering the barn is filtered of pathogens that can be airborne. For this reason a number of companies provide systems for filtering the air at the intakes. Typically the air intakes communicate with the roof space with the air entering into the containment area through the ceiling and also from the wall. This can be done by providing filtration membranes engaging the air as it enters the roof space or it can be done by providing on each intake duct a separate membrane assembly attached onto the intake opening within the roof space.

Much work has been done, for example by Noveko of Quebec, on developing improved membranes which provide an effective and cost efficient filtration system. However it is known that pathogens can still enter the containment area by the fans louvers and disease can still strike, often with very damaging results.

However it is known that pathogens can still enter the containment area through closed fans louvers, due to known negative air pressure (0.05 inch of water) inside the building. It has been experimented that a 24″ fan that is not running even with the louvers closed, can allow in as much as 400 cfm of viral contaminated air into the building, and that 3×24″ fans can allow in as much viral contaminated air into a building as a 12″ running fan would do if it were used to push viral contaminated air into a building, which may cause airborne pathogen to strike, often with very damaging results.

The animals concerned are typically pigs and poultry but of course other animals require the same protection from pathogens that can be airborne.

SUMMARY OF THE INVENTION

It is one object of the invention to provide a fan construction for use in an animal husbandry barn.

According to one aspect of the invention there is provided a fan construction for use in an animal husbandry barn where the barn comprises:

a containment area;

a plurality of air inlets into the containment area where each air inlet has an air filter system for extraction from incoming air of pathogens so as to prevent transmission of disease to the animals;

and a plurality of extraction fan constructions for generating an air stream exiting the containment area so as to draw replacement air into the containment area through the air inlets;

each fan construction comprising:

-   -   a fan housing arranged to be mounted in a wall;     -   the fan housing having an inlet opening at the wall and an         outlet duct extending through the wall to an outlet opening         outside the wall;     -   a fan mounted in the housing;     -   and a damper flap assembly mounted on the fan housing, the         damper flap assembly including:     -   a mounting plate having an opening through which the air passes         and a flange surrounding the opening;     -   a damper flap suspended by a hinge at an upper edge and pivotal         about the upper edge so as to extend in a closed position across         the opening with an outer peripheral portion of the damper flap         engaging the flange around the opening;     -   the damper flap being movable to an open position under forward         air flow from the fan by pivoting on the hinge away from the         flange;     -   and a resilient deformable seal between the outer peripheral         portion of the damper flap and the flange arranged to seal the         damper flap to prevent reverse flow of air through the fan         housing.

The seal is preferably carried on the outer peripheral portion of the damper flap but it can also be located on the flange.

Preferably the seal comprises a deformable fin of a type which can readily deform under the relatively low forces involved from gravity on the damper flap and from back pressure of reverse air flow so that a sealing effect is obtained.

Typically the opening is rectangular although other shapes are also possible particularly circular.

Preferably the mounting plate includes a top cover extending from the hinge over the top of the damper flap to maintain protection from falling contaminants such as snow and preferably the top cover has a down-turned flange to engage the damper flap and prevent pivotal movement of the damper flap beyond a predetermined angle.

Preferably there is provided an abutment member, such as a pin carried on the mounting plate, for holding the damper flap in a slightly open position, the abutment member being retractable for example by an electrically operable remote control device to allow closing of the damper flap. The key point is the provision of the abutment, which acts to hold the flap slightly ajar to allow the low airflow to escape with a protection against the wind forces. Other shapes and arrangement of abutment member can be used and these can be actuated in many different ways than the electrical solenoid primarily proposed.

Preferably there is provided a latch for providing a closing force for holding the damper flap in the closed position to provide an increased closing force when the flap is closed but allowing release to the open position as soon as the air flow generates enough force to overcome the latch. The latch can be a magnetic strip around the periphery of the damper flap or a magnet located at the bottom edge of the damper flap. Other types of latch or system can be used for example a spring or counterweight etc, to assist in holding the flap in the closed position which latch is released as soon as the air flow operates to move the flap away from the closed position.

Preferably the damper flap comprises flat panel which may be an insulated panel of a foam material or similar stiff flat member. Other constructions of flap can be used which may not necessarily be insulated.

Preferably the damper flap assembly is mounted on outside end of the fan housing. In this case the fan housing may retain or include an additional louver closure at the wall opening.

Alternatively the damper flap assembly can be mounted on the fan housing at the wall opening inside the building.

There may be provided a heating wire for heating the seal to prevent freezing.

Preferably the hinge is a flexible strip extending from the damper flap to the mounting plate and mounted on a spacer strip at the mounting plate. Other types of hinge can also be used with the intention that they are resistant to jamming or freezing and they are not restricting the airflow.

Preferably the air inlets are arranged at the ceiling of the containment area communicating with a roof space above the containment area. However other locations of the filtered air inlets are possible and many different designs of barn ventilation can be used. Preferably each air inlet includes a filter assembly carried in the roof space. However the air flow into the roof space through the eaves can be filtered by exterior mounted filters added on the outside of the building. It is of course intended that, apart from the inlets and the extraction fans, the containment area is sealed against ingress of pathogen containing air.

The arrangement described above can have two different and independent objectives. Firstly to block the virus contained in air back-draft, from infiltrating fan louver when a fan is not running in air-filtered barn for swine and also for poultry barn. Secondly to block the wind effect against the fan when a fan is running at slow or minimum speed to prevent air-back draft pathogen contamination.

It has been determined that the conventional louver arrangement used with agricultural fans is not sealed enough to prevent back-draft and virus contamination.

According to a second aspect of the invention there is provided a fan construction comprising:

a fan housing;

a fan mounted in the housing;

the fan being operable at high speed and at low speed;

and a damper flap assembly mounted on the fan housing, the damper flap assembly including:

a mounting plate having an opening through which the air passes and a flange surrounding the opening;

a damper flap suspended by a hinge at an upper edge and pivotal about the upper edge, so as to extend in a closed position across the opening with an outer peripheral portion of the damper flap engaging the flange around the opening;

the damper flap being movable to an open position under forward air flow from the fan when the fan is operating at low or high speed, by pivoting on the hinge away from the flange;

wherein there is provided an abutment member for holding the damper flap in a slightly open position against opposing wind forces, when the fan is operating at low speed.

Thus the flap and the pin action control the minimum ventilation rate for the fan when the fan faces wind forces. This can be used both in air-filtered barns and even for barns without air filters.

The addition of the pin at the bottom of the panel is used in order to be able to keep a continuous minimum opening which can vary from 0.5 to 6 inch according to the remote adjustment of the pin. Then, even if the slow running fan faces a lot of wind, the damper will stay open and the air can be easily blown out by the fan, preventing air back-draft pathogen contamination in air-filtered barns. In the case of barns that are not air-filtered, the objective is not to prevent virus transmission but only to control the minimum ventilation rates even with or without windy conditions. The purpose is to improve the air quality inside the barn even if winds faces the fans. This will allow an easy minimum ventilation rates adjustment for the operators and reduced energy cost for fan operation and building heating.

In order to have a better minimum ventilation rate control, the standard louvers installed on the fan can be removed.

In a filtered building, this arrangement can allow the number of fans in the first and second ventilation stage to be reduced by using larger fans, which provide both reduced contamination risk by virus from air back-draft and also reduced energy consumption. With higher flow rates on the first and second ventilation stage, this will also allow to reduce the number of fans on stage three and more. In some cases, this feature will allow to avoid the use of stage three and more.

In non-filtered swine and poultry barn, this feature allows a better minimum ventilation rate control during windy period. When the wind comes in the fan direction, this has a restriction effect on the fan's airflow. When a fan is running at its minimum speed, a strong wind can almost totally block the airflow and cause air quality problem inside the building because the contaminants are still in the barn. Then, this equipment will help to optimized the air quality control and the heating cost in the barns. Also, this concept can allow to reduce the number of fans on first and second ventilation stage by using larger fans and reduced energy consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

FIG. 1 is a plan view of a barn including a fan construction according to the present invention;

FIG. 2 is a vertical cross-sectional view of the barn of FIG. 1;

FIG. 3 is a cross-sectional view along the same lines as FIG. 2 on a much enlarged scale showing one fan construction with the closure flap thereof in an open position;

FIG. 4 is a front elevational view of the fan construction of FIG. 3.

FIG. 5 is a cross-sectional view on a further enlarged scale than FIG. 3 showing one part only of the fan construction with the closure flap thereof in a closed position with the magnet at the bottom part of the flap;

FIG. 6 is a cross-sectional view on a further enlarged scale than FIG. 3 showing one part only of the fan construction with the closure flap thereof in a partly open position held opened by a pin;

FIG. 7 is a cross-sectional view of a modified embodiment on a further enlarged scale than FIG. 3 showing one part only of the fan construction with the closure flap thereof in the closed position with the magnet on the perimeter of the flap;

FIG. 8 is a cross-sectional view similar to that of FIG. 3 showing a modified fan construction with the closure flap assembly thereof at the inlet end at the wall opening inside the building.

FIG. 9 is a cross-sectional view similar to that of FIG. 3 showing a modified fan construction which has no exterior duct on the fan housing so that the closure flap assembly thereof is mounted on the fan housing directly at the wall opening outside the building.

FIG. 10 is a cross-sectional view similar to that of FIG. 3 showing a modified fan construction which provides more than one row of closure flaps.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

In FIGS. 1 and 2 is shown an animal husbandry barn 100 including peripheral walls 101 defining a containment area 102. A roof 103 defines a roof space 104 above a ceiling 105.

A plurality of air inlets 106 provide air entry into the containment area where each air inlet 106 has an air filter system 107 for extraction from incoming air of pathogens so as to prevent transmission of disease to the animals.

A plurality of extraction fans 110 are located at spaced positions around the walls for generating an air stream exiting the containment area so as to generate a negative air pressure within the barn so as draw replacement air into the containment area through the air inlets 106. Apart from the inlets and the extraction fans, the containment area is sealed against ingress of pathogen containing air.

The extraction fans can be driven at variable rate including at least high and low speed and can be shut off when not required. Shutting off fans when possible of course reduces energy usage. High fan speed is required at the highest temperatures to provide the required level of ventilation and cooling. Lower fan speed is required at other times. The system can be computer controlled to ensure sufficient ventilation and cooling while minimizing energy usage.

As shown in FIG. 3, each fan has a fan housing 17 defining a duct extending from an end plate 17A which mounts in the wall 101. The plate and duct form a circular or rectangular passage for air escaping from the wall opening. A fan 18 with a motor 18A and fan blades 18B is mounted in the duct of the fan housing to drive the air outwardly from the wall opening to an open end 17C of the fan housing 17. The open end 17C thus forms an opening spaced outwardly from the wall 101.

The fan housing thus defines an inlet opening 17D at the wall and an outlet duct 17 extending through the wall to an outlet opening 17C outside the wall.

A damper flap assembly 120 is mounted on the fan housing which includes a mounting plate or board 12 having an opening 12A through which the air passes and a flange 12B surrounding the opening and defining top flange 12C, bottom flange 12B and side flanges. A flexible rubber seal or silicon 10 allows to seal the joint between fan housing 17 and the mounting plate 12.

A damper flap 1 in the form of a Styrofoam or similar board covered with a plastic sheet on each surface and covering the edges. The board or flap 1 is suspended by a hinge 16 at an upper edge engaging the top flange 12C. The board 1 is pivotal about its upper edge so as to hang from the hinge under gravity. The board 1 can therefore extend in a closed position across the opening 12A with an outer peripheral portion 1A, 1B, 1C and 1D (FIG. 4) of the damper flap engaging the flange 12B, 12C around the opening 12A.

The damper flap 1 is movable to an open position as shown in FIG. 3 under pressure from forward air flow 18F from the fan 18 by pivoting on the hinge 16 away from the flange 12B, 12C.

A resilient deformable fin seal 2 is provided on the peripheral portions 1A, 1B, 1C and 1D so as to act between the outer peripheral portion of the damper flap and the flange. The seal surrounds the opening 12A and is arranged to seal the damper flap to prevent reverse flow 18R of air through the fan housing.

The seal comprises a deformable fin 2A (FIG. 6) which can be readily depressed and provide an effective seal under the low forces of back pressure from the negative air pressure inside the building.

The mounting plate 12 includes a top cover 13 extending from the hinge 16 outwardly over the top of the damper flap 1 and includes down-turned flange 14 with a bottom edge 14A to engage the damper flap 1 and prevent pivotal movement of the damper flap 1 beyond a predetermined angle. The cover 13 can also include side plates 11 which prevent air from engaging the sides of the flap 1.

In operation, the flap is held open by air flow at a high rate from the fan 18 in the forward direction 18F. In the event that the fan is shut off when the air flow is not required, the flap closes under gravity until it engages the plate 12 causing the seal to engage. In this case the back pressure on the flap will hold it closed forming a seal to prevent back flow of any contaminated air into the building. This is particularly important in times of the year such as Fall or Spring where the outside temperature is not sufficiently high that high fan flow is required, and when the minimum ventilation causes the air to be humid and slow moving, leading to high levels of contaminants.

In order to hold the flap slightly open during times when the fan is driven at a lower rate for less air movement, an abutment member 7 is provided for butting the bottom edge portion 1C holding the damper flap in a slightly open position. The abutment member 7 includes a pin 7A which is retractable on a solenoid 7B mounted on a plate 6 underneath the fan housing 17 on the rear of the plate 12 to allow closing of the damper flap. Thus the pin is electrically operable by a remote control device for full retraction to allow closing and for adjustment to set the required amount of opening depending on required air flow rate.

In order to increase the closing pressure to supplement the back air pressure, a magnet latch is provided for providing a closing force for holding the damper flap in the closed position. This can comprise a magnetic strip 20 around the periphery of the damper flap cooperating with a metal strip 21 on the mounting plate 12.

Alternatively the magnet latch comprises a magnet 3 carried on a support plate 4 and cooperating with a metal plate 5 on the mounting plate 12 located at the bottom edge of the damper flap.

A heating wire 8 can be provided for heating the seal to prevent freezing.

The hinge 16 is a flexible strip across the top of the flap 1 and extending from the damper flap 1 to the mounting plate 12 and mounted on a spacer strip 15 at the mounting plate 12. Other types of hinge can be used.

The typical additional louver closure 19 remains in some cases at the wall opening to provide an interior closure when the fan is shut off.

The arrangement described above includes a fan housing with an exterior duct, which extends outwardly of the wall where the damper flap assembly is mounted on an outer end of the duct.

In FIG. 8 is shown a cross-sectional view similar to that of FIG. 3 showing a modified fan construction with the damper flap assembly thereof at the inlet end at the wall opening. In this case the device is located in front of the louver arrangement 19, which can be removed or may remain in place. Apart from this modification, the construction is the same as that described above. In FIG. 8, the damper flap will not act to block the wind effect at low speed because it is installed upstream from the fan. So that, in that case, the only objective is to block the contaminated reverse flow of the air in the back-draft. Thus the solenoid abutment is not required. A solenoid may be provided to open the flap when the flap is blocked by freezing. A duct 22 which can be rectangular or circular is located between the damper flap and the fan inlet. This duct is suitably fastened to the wall.

In FIG. 9 is shown a cross-sectional view similar to that of FIG. 3 showing a yet further modified fan construction with no duct so that the damper flap assembly thereof is mounted directly at the outside surface of the wall. In this arrangement there is provided a wire mesh 18D on the inside surface at the fan 18B as a protection guard and a fan venturi 18G. In this arrangement the louvers 23 are mounted on the outside of the wall with its box insert into the wall. There may be provided also a short duct 24 between the wall and the damper flap. Apart from this modification, the construction is the same as that described above.

In FIG. 10 there is shown an arrangement with two rows of flaps 120. This arrangement can be used for example with a 36 inches fan. The flap dampers can be either installed inside or outside the building as described above. In some constructions there also be more than two rows as well as more than 1 column of flaps for example for 55 inches fans.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense. 

1. A fan construction for use in an animal husbandry barn where the barn comprises: a containment area; a plurality of air inlets into the containment area where each air inlet has an air filter system for extraction from incoming air of pathogens so as to prevent transmission of disease to the animals; and a plurality of extraction fan constructions for generating an air stream exiting the containment area so as to draw replacement air into the containment area through the air inlets; each fan construction comprising: a fan housing; a fan mounted in the housing; and a damper flap assembly mounted on the fan housing, the damper flap assembly including: a mounting plate having an opening through which the air passes and a flange surrounding the opening; a damper flap suspended by a hinge at an upper edge and pivotal about the upper edge so as to extend in a closed position across the opening with an outer peripheral portion of the damper flap engaging the flange around the opening; the damper flap being movable to an open position under forward air flow from the fan by pivoting on the hinge away from the flange; and a resilient deformable seal between the outer peripheral portion of the damper flap and the flange arranged to seal the damper flap to prevent reverse flow of air through the fan housing.
 2. The fan construction according to claim 1 wherein the seal is carried on the outer peripheral portion of the damper flap.
 3. The fan construction according to claim 1 wherein the seal comprises a deformable fin.
 4. The fan construction according to claim 1 wherein the mounting plate includes a top cover extending from the hinge over the top of the damper flap.
 5. The fan construction according to claim 4 wherein top cover has down-turned flange to engage the damper flap and prevent pivotal movement of the damper flap beyond a predetermined angle.
 6. The fan construction according to claim 1 wherein there is provided an abutment member for holding the damper flap in a slightly open position against opposing wind forces when the fan is operating at a low speed.
 7. The fan construction according to claim 1 wherein the abutment member is retractable to allow closing of the damper flap.
 8. The fan construction according to claim 6 wherein the abutment member is operable by a remote control device.
 9. The fan construction according to claim 1 wherein there is provided a latch for providing a closing force for holding the damper flap in the closed position.
 10. The fan construction according to claim 9 wherein the latch comprises a magnetic strip around the periphery of the damper flap and/or a magnet at the bottom of the flap.
 11. The fan construction according to claim 1 wherein the damper flap comprises a flat panel which may be insulated.
 12. The fan construction according to claim 1 wherein the damper flap assembly is mounted on outside end of the fan housing.
 13. The fan construction according to claim 1 wherein the fan housing has an additional louver closure.
 14. The fan construction according to claim 1 wherein the damper flap assembly is mounted on the fan housing at an inner end.
 15. The fan construction according to claim 1 wherein there is provided a heating wire for heating the seal to prevent freezing.
 16. The fan construction according to claim 1 wherein the air inlets are arranged on the wall and/or at the ceiling of the containment area communicating with a roof space above the containment area.
 17. The fan construction according to claim 16 wherein each air inlet includes a filter assembly carried in the roof space.
 18. The fan construction according to claim 1 wherein, apart from the inlets and the extraction fans, the containment area is sealed against ingress of pathogen containing air.
 19. A fan construction comprising: a fan housing; a fan mounted in the housing; the fan being operable at high speed and at low speed; and a damper flap assembly mounted on the fan housing, the damper flap assembly including: a mounting plate having an opening through which the air passes and a flange surrounding the opening; a damper flap suspended by a hinge at an upper edge and pivotal about the upper edge so as to extend in a closed position across the opening with an outer peripheral portion of the damper flap engaging the flange around the opening; the damper flap being movable to an open position under forward air flow from the fan when the fan is operating at low or high speed by pivoting on the hinge away from the flange; wherein there is provided an abutment member for holding the damper flap in a slightly open position against opposing wind forces when the fan is operating at low speed.
 20. The fan construction according to claim 19 wherein the abutment member is retractable to allow closing of the damper flap.
 21. The fan construction according to claim 20 wherein the abutment is operable by a remote control device. 